Investigation of Fouling in Gas/Particle Flow

Abstract

This thesis discusses particulate fouling of heat exchangers. In the metallurgical industries, the waste gas may contain dust and particles, which deposit on the heat exchanger surfaces. The thesis focuses on numerical simulations of the particles migration through the boundary layer at the surface of the heat exchanger, and the different transport rates regarding different particle sizes. An introductory to boundary layer theory is included. Some mechanisms of turbulent flow are also presented, as turbulence is important for the analysis of particle transportation. A brief introduction to Ansys Fluent, the software used for simulations, is provided.Flow analysis in Ansys Fluent if performed on the flat plate geometry tested in the project work. Simulated and analytic boundary layer calculations are compared to validate the flow field. Numerical simulations of particle deposition are performed on a tilted flat plate. The results are compared to the observations and findings from the laboratory work in the project thesis.It will be shown that the collision rate between the particles and the heat exchanger surface is highly dependent on particle size.Suggestions for further work are given at the end of the thesis